Synergetic surface charge transfer doping and passivation toward high efficient and stable perovskite solar cells

Abstract

Summary Organic-inorganic lead halide perovskite solar cells (PSCs) have received much attention in the last few years due to the high power conversion efficiency (PCE). Generally, perovskite/charge transport layer interface and the defects at the surface and grain boundaries of perovskite film are important factors for the efficiency and stability of PSCs. Herein, we employ an extended benzopentafulvalenes compound (FDC-2-5Cl) with electron-withdrawing pentachlorophenyl group and favorable energy level as charge transfer molecule to treat the perovskite surface. The FDC-2-5Cl with pentachlorophenyl group could accept the electrons from perovskite as a p-type dopant, and passivate the surface defects. The p-type doping effect of FDC-2-5Cl on perovskite surface induced band bending at perovskite surface, which improves the hole extraction from perovskite. As a result, the PSC with FDC-2-5Cl treatment achieves a PCE of 21.16% with an enhanced open-circuit voltage ( V oc ) of 1.14 V and outstanding long-term stability.

Unraveling Passivation Mechanism of Imidazolium-Based Ionic Liquids on Inorganic Perovskite to Achieve Near-Record-Efficiency CsPbI2Br Solar Cells

“…This is indicative of reduced recombination and enhanced charge extraction at the perovskite/IILs interface, which is consistent with the PL and TRPL results (Fig. 1e, f) [12,[37][38][39].…”

Dithiol surface treatment towards improved charge transfer dynamic and reduced lead leakage in lead halide perovskite solar cells

“…In Figure 1C, after 1,2‐EDT treatment, Pb 4f 7/2 and Pb 4f 5/2 peaks similarly shift to lower binding energies from 138.1 to 143.0 to 137.6 and 142.5 eV, respectively. According to previous reports, this shift trend of Pb 4f peaks may result from the surface p‐type doping 28,29 . It can also be noticed that the 136.5 and 141.4 eV positions show two weak peaks in the spectrum of the conventional perovskite correspond with Pb 0 state, while they are not detected in the 1,2‐EDT treated film.…”

“…According to previous reports, this shift trend of Pb 4f peaks may result from the surface p-type doping. 28,29 It can also be noticed that the 136.5 and 141.4 eV positions show two weak peaks in the spectrum of the conventional perovskite correspond with Pb 0 state, while they are not detected in the 1,2-EDT treated film. We could conclude that the metallic Pb was forming during XPS measurements 28 and 1,2-EDT prevented its formation as well as Pb leakage.…”

“…The 1,2‐EDT treated electron‐only devices manifest low V TFL value (0.11 V) compared with conventional devices (0.39 V). According to the equation N trap = (2 εε 0 V TFL )/( eL 2 ), we can quantify the trap density 29,36 . In this equation, ε stands for relative dielectric constant, ε 0 represents the vacuum permittivity, e is the elementary charge and L represents the thickness of perovskite film.…”

Enhanced Efficiency and Stability of All‐Inorganic CsPbI2Br Perovskite Solar Cells by Organic and Ionic Mixed Passivation

“…Organic–inorganic hybrid perovskite solar cells (PSCs) have aroused significant interests of many researchers worldwide in the past decade. [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ] Their inherent superior optoelectronic features have made the power conversion efficiency (PCE) up to the current topmost 25.5% which rivals the commercial monocrystalline silicon solar cells. [ 11 ] Despite the outstanding performance, organic–inorganic hybrid PSCs still suffer stability issues originated from the organic monovalent cations, such as methylammonium (known as MA + or CH 3 NH 3 + ) and formamidinium (knowns as FA + or CH(NH 2 ) 2 + ).…”